Method and composition for coating pre-sized paper with a mixture of a polyacid and a polybase

Abstract

The present invention features coating compositions and methods for improving the quality of images printed on a paper substrate. The novel coating compositions contain a coating agent comprising a mixture of a polyacid and a polybase. When applied to a sized paper substrate, the coating compositions provide a coated paper substrate that provides high quality printed images when printed with an ink containing a reactive dye having ionizable and/or nucleophilic groups capable of reacting with the coating agent. Images printed on a paper substrate coated with the coating composition of the invention are bleed-resistant, water-resistant (e.g., water-fast), and/or are characterized by an enhanced chroma and hue.

Description

The present invention relates generally to the production of coated paper, and more particularly relates to a novel paper coating process and novel compositions useful in conjunction therewith.As printing technology advances, paper manufacturers are faced with the increasingly rigorous demands of their customers for high quality paper that is economically attractive. For example, there is a keen demand for papers that meet high quality standards with respect to brightness, opacity, and dry and / or wet strength, and that, upon printing with any of a wide range of colorants, provide a water-resistant printed image. The customer further demands that such papers be amenable to use with a variety of printing techniques, including not only conventional printing techniques, but also "impact free" printing techniques such as inkjet printing (particularly colored inkjet printing), laser printing, photocopying, and the like.In response, paper manufacturers have attempted to meet their customer...

AI Technical Summary

Benefits of technology

The present invention is based upon the discovery that a composition containing a coating agent comprising a mixture of a polyacid and a polybase is effective in coating a sized paper substrate to provide numerous advantages. Coated paper substrate that has been treated with a coating composition of the invention yields high quality printed images having improv

Problems solved by technology

Although these materials are effective to various degrees under certain conditions, use of each is associated with certain limitations.

However, the opacity and brightness of the paper substrate decrease in direct proportion to the amount of sizing agent applied to the paper.

Moreover, as the amount of sizing agent and/or the cost of the sizing agent increases, the cost of producing the paper increases, making high quality papers prohibitively expensive.

Certain sizing agents impart relatively poor bleed resistance and water resistance of imprinted inks, and thus must be used with insolubilizing agents to ensure production of a printed paper having satisfactory water resistance.

However, while starches may provide improved porosity, these compounds generally do not provide for improved bleed resistance or water resistance of inks printed on the treated paper substrates.

However, synthetic sizing agents tend to be expensive, due to both the cost of the starting material and the amount that is required to provide a paper